MacOs has VoiceOver built-in, which is free.
The web is also quite accessible by default. I worked for the a11y branch of a big webapp, px fonts and such are not that big of a problem.
MacOs, Windows, and ChromeOS are devmcent. Linux as usual is a cluster fuck - it has basic functionality available, but it is lacking almost all features from what I can tell - e.g. skipping words/paragraphs, listing links/headings/forms/inputs/landmarks etc. I don't test on Linux as I figure that anyone who needs to use a screen reader won't be using Linux as the support seems to awfully backwards compared to other OSs